After a few martinis, George Sprague realized there would be no better way to renew his vows and celebrate his 50th wedding anniversary than underwater. With a mermaid present.

In January, Sprague and his wife, Lee, were watching the mermaid show that takes place Friday and Saturday nights in the pool behind the porthole windows of the Sheraton Fort Lauderdale Beach Hotel’s Wreck Bar when the idea first occurred to the couple.

At first, George Sprague was skeptical.

“I said, ‘What? I’m 75 years old, I don’t think I’ll be jumping in the pool with the mermaids,’ ” he said.

But a few drinks in, the idea didn’t seem so bad after all. It didn’t seem too bad the next morning either, when he and Lee decided to take the plunge.

“Why not?” she said.

The part-time locals were the first to participate in the hotel’s new underwater mermaid wedding package, which launched this spring for couples hoping to give their ceremony the chlorine touch it was missing.

The affair comes with an underwater session including up to three mermaids during a 90-minute reception at the Wreck Bar. The $95-per-guest cost includes open bar, appetizers, champagne toast, a legal wedding ceremony including officiant, one how-to-be-a-mermaid lesson and a bride-and-groom photo shoot. Mermaid tails for the happy couple are also included but are not mandatory.

The Sheraton’s general manager, Amaury Piedra, said the idea is meant to provide a unique alternative to the many couples who are married at the Sheraton’s private beach.

Couples can personalize their experience, he said, getting married on the beach and then jumping in the pool with the mermaids to dazzle their guests, or have their ceremony by the pool and then go underwater. To supplement their ordained ceremony, guests can exchange vows underwater with the help of signs, if they choose to. What they don’t use is snorkels; this is a real hold-your-breath moment.

For those with rusty mermaid techniques, additional lessons with lead mermaid Marina Anderson cost extra.

“It’s something different for the water enthusiasts,” Piedra said.

The Spragues, adventurous snowbirds whose exploits have included zip lining in Alaska and a trip to South Africa amid riots, wanted to make their 50th anniversary celebration a wet one.

“It was certainly very unusual,” said George Sprague, a retired Massachusetts district court judge. “Our friends in New England probably thought we were sitting in the sun too long.”

“It took us out of our comfort zone,” Lee Sprague, 73, agreed.

The Boston natives met as teenagers at a dancing school, started a 10-year courtship and married in September 1964 in a big church ceremony — no mermaid tails included. They moved to Fort Lauderdale in 2011 and haven’t lost the sense of humor they said has helped them stay together so many years.

When they signed up for their mermaid wedding vow renewal, they could only hold their breaths for 10 to 15 seconds each. After two months of mermaid practice at their Fort Lauderdale complex pool, they could hold their breaths for 45 seconds, enough to put on a show for their guests.

Lead mermaid Anderson trained them to blow bubble kisses at their guests, be comfortable in the water and stay submerged.

The life of a mermaid is a difficult one, Lee Sprague learned. Every time she was submerged she popped back up to the surface like a buoy. Anderson outfitted her with an 8-pound weight belt and showed her how to position her hands and body gracefully underwater.

“They were troopers,” Anderson said. “Here’s a couple that was ready to go under and they would.”

On March 30, George and Lee Sprague donned their ceremony attire. Both wore aquamarine swimsuits and white T-shirts. His read: Will you remarry me? Hers: You betcha!

In a rainbow flower petal cap and goggles Lee Sprague walked down the aisle with her husband and exchanged vows at a white altar by the pool.

Then the 40 guests moved into the Wreck Bar, which was featured in the movie Analyze This, and waited for the couple to appear behind the windows. They swam down to the portholes, waving at the guests and smiling up to their goggles with Anderson in her blue tail at their side. The Spragues decided to forgo the tails; the groom said “that was a little much.”

General Manager Piedra said many couples have inquired about the mermaid wedding package, although no other weddings are yet booked, and he said he hopes to book weddings once a month.

The Spragues laughed imagining what people would say about their out-of-ordinary plunge, but for them, it was the perfect thing to do.

“I can’t imagine what some of the defendants who I sent to jail would think if they saw me with mermaids,” George Sprague joked.

Their two children are throwing them a more traditional party in Boston in October with family and friends to cap off a year of celebrations.

“I don’t think the mermaids will be invited to Boston,” George Sprague said.